3 hours free, but no where to do them. That was the 1st half of my 20s. Doing them in an apartment complex parking lot was risking eviction for lease violation. Doing that work on the side of the road could risk tickets and the like. There are plenty of reasons one may not have the capacity to do something as time consuming as a brake job. I can do my entire vehicle in about 45 mins in my driveway. Someone new to wrenching could easily spend those 3 hours on a single corner, especially if ill-equipped for rust belt misery.